Milbeaut Image Signal Processing LSI Chip for Mobile Phones
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17 FUJITSU Sci. Tech. J., Vol. 49, No. 1, pp. 17–22 (January 2013) Milbeaut Image Signal Processing LSI Chip for Mobile Phones Satoru Komatsu Mitsumaro Kimura Akira Okawa Hideaki Miyashita The camera function of mobile phones has progressed in the last few years, as typified by the rapid spread of high pixel count, high resolution, and full high-definition video recording and playback features in smartphones. Although it is possible to implement camera functions such as rapid imaging and browsing from personal computers and mobile terminals into the applica- tion processor in a mobile phone, many customers prefer dedicated image signal processors (ISPs) as they offer image quality and performance comparable to those of compact high-end digital cameras. This paper describes the development and performance of the Milbeaut Mobile image processing LSI chip developed by Fujitsu for mobile phones. 1. Introduction The market for smart mobile phones continues to expand due to their diverse applications and functions. The camera function in particular has been evolving steadily since it was introduced to mobile phones in 2000 and is now a major mobile phone function, pro- viding high-pixel count and high resolution as well as full high-definition video recording and playback. Milbeaut Mobile is a series of image signal pro- cessors (ISPs) for use by the camera function in mobile phones. It was developed by Fujitsu and has been on the market since 2003. Here, we present an overview of the Milbeaut Mobile series and describe the system architecture, features, functions, and processing per- formance of the MBG046, the latest Milbeaut Mobile processor. 2. Evolution in Milbeaut Mobile functionality The camera function is achieved by using a spe- cialized lens and image sensor that must be small and thin for mounting on mobile phones. These constraints initially prevented image quality from being as good as that of digital cameras. An ISP must therefore be able to raise the quality of images captured by a lens and image sensor under such severe constraints to a level satisfactory to users. By 2008, the 3rd generation Milbeaut Mobile ISP incorporated such digital camera functions as still-im- age continuous automatic focus (CAF), face detection, and electronic motion compensation (Figure 1). The latest generation ISP (the MBG046) incorporates nearly all camera functions. It also features full high-defi- nition (1920 × 1080 pixels) video, video CAF, and 3D video imaging as demanded by the market. The recent achievement of a further reduction in imaging device pixel size, a higher pixel count, and faster imaging has caused problems with image quality and has increased ISP power consumption. 3. ISP architecture The image processor module is the main func- tional component of the Milbeaut Mobile ISP (Figure 2). It sequentially processes the image data received in the Bayer array signal from the image sensor, includ- ing noise removal and other corrective functions, to produce a beautiful image and conversion into a for- mat for display on the screen of a mobile terminal or personal computer. The module can also access hardware image filters and the CPU to perform additional processing (rotation and distortion correction, software image processing,
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